The proposal is concerned with various aspects of lipid transport in avian species, with an emphasis on studies of lipoprotein lipase (LPL) in various tissues and transport of lipoprotein constituents into the avian ovarian oocytes. The following hypotheses will be tested: (1) Short term regulation of LPL in heart tissue, adipose tissue and ovarian granulosa cells is mediated in large part via increase in enzyme state of activation. (2) Increased state of activation is a result of dephosphorylation of enzyme protein. (3) LPL is synthesized in adipocytes. (4) These are specific LPL binding sites on the endothelial cell adipocytes and granulosa cell plasma membranes. Testing these hypotheses will be made possible by the availability of highly purified adipose tissue LPL, specific LPL antibody, and quantitative LPL immunotitration methods. Changes in enzyme state of activation will be induced in vivo with insulin, glycagon, anti-insulin serum, and mannoheptulose feeding. LPL regulation will also be studied in vitro with surviving fat pads and granulosa cells maintained in culture. Variations in state of activation determined by immunotitration will be corrected with level of phosphorylation of LPL as measured by the ratio of (32P) to (3H) leucine incorporation in enzyme protein. LPL will be localized in adipose, heart and granulosa cell culture by electron microscopy and autoradiography following exposure of tissues to a highly specific (125I) anti-LPL immunoglobulin. Existence of binding sites on plasma membranes of adipocytes, endothelial cells and granulosa cells will be established by measuring specific binding of (125I) LPL to these cells. The amino acid and carbohydrate composition of heart and adipose tissue LPL will be compared. The ability of ovarian granulosa cells to degrade very low density lipoprotein (VLDL) apoproteins and incorporate labeled amino acid precursors into resynthetized VLDL apoprotein will be investigated in cell culture. Two methods with wide applications in the lipoprotein field will be validated: The first one concerns the in vitro labeling of VLDL triglyceride; the second, the quantitative measurements of lipoprotein polypeptides separated by disc gel electrophoresis.